A number of crypto points:
1) Crypto is incredibly complex
2) Crypto algorithm design is incredibly complex
3) Crypto protocol design is incredibly complex
If you don't believe this, then as a warm up exercise, explain why
HMAC-MD5(k, text) is not just MD5(k . text) (where . represents
concatenation).
4) Use crypto design/protocols that are designed by real experts and
have been tested by real experts.
If you want to be humbled, then attend
http://web.mit.edu/professional/summer/courses/6.87s.html for a week
long intensive course on cryptography. I did the class a few years ago
and I came away realizing how little I knew -- and consequently I was a
lot less dangerous! I cannot recommend this class too highly. In the
year that I took it, the majority of the class was from Fort Meade!
Philip
--
Philip Gladstone
* Check out the live pondcam at http://pond.gladstonefamily.net